Redwood farm

x,y,z = 0,0,0

function moveUp()
	if turtle.up() then
		z = z + 1
		return true
	end
end

function moveDown()
	if turtle.down() then
		z = z - 1
		return true
	end
end

function moveFor()
	if turtle.forward() then
		x = x + 1
		return true
	end
end

function moveBack()
	if turtle.back() then
		x = x - 1
		return true
	end
end

function moveRight()
	turtle.turnRight()
	turtle.dig()
	if turtle.forward() then
		y = y + 1
		turtle.turnLeft()
		return true
	else
		turtle.turnLeft()
		return false
	end
end

function moveLeft()
	turtle.turnLeft()
	turtle.dig()
	if turtle.forward() then
		y = y - 1
		turtle.turnRight()
		return true
	else
		turtle.turnRight()
		return false
	end
end

function mineUp()
	turtle.dig()
	turtle.digUp()
	moveUp()
end

function mineDown()
	turtle.dig()
	turtle.digDown()
	moveDown()
end

function mineFor()
	turtle.dig()
	moveFor()
end

function dropOff()
	print("Dropping off items..")
	turtle.turnRight()
	turtle.turnRight()
	for i=2,16 do
		turtle.select(i)
		turtle.drop()
	end
	turtle.turnRight()
	turtle.turnRight()
end

function waitGrow()
	print("Waiting for grow..")
	turtle.select(1)
	while turtle.compare() do
		os.sleep(10)
	end
	print("Tree grew!")
	return true
end

function placeSapling()
	turtle.select(1)
	if turtle.getItemCount(1) < 4 then
		print("Ran out of saplings.")
		return false
	else
		print("Planting new tree.")
	end
	moveFor()
	turtle.place()
	moveRight()
	turtle.place()
	moveBack()
	turtle.place()
	moveLeft()
	turtle.place()
	return true
end

function chopTree()
	print("Chopping tree.")
	mineFor()
	while turtle.detect() do
		mineUp()
	end
	moveRight()
	while z ~= 0 do
		mineDown()
	end
	turtle.dig()
	moveBack()
	moveLeft()
end

function farm()
	if not placeSapling() then
		return false
	end
	waitGrow()
	chopTree()
	dropOff()
	if x ~= 0 or y ~= 0 or z ~= 0 then
		return false
	end
	os.sleep(1)
	return true
end

while true do
	if not farm() then
		print("Something went wrong.")
		return
	end
end